1. Field of the Invention
The present invention relates to alcohols, to apparatus for producing alcohols, to a method of producing alcohols, and to a method of producing esters from alcohols. In another aspect, the present invention relates to alkylene glycols, to apparatus for producing such glycols, to a method of producing such glycols, and to a method of producing esters from such glycols. In yet another aspect, the present invention relates to alkylene glycols having an increased primary hydroxyl content, to apparatus for producing such glycols which include one or more continuous stirred tank reactors in series feeding a plug flow reactor, to a method of producing such glycols from a reaction mixture of water, lower order alkylene glycols, alkylene oxide and acid, and to a method of producing acrylate esters from such glycols.
2. Description of the Related Art
Monoalkylene glycols are generally produced by the hydrolysis of the alkylene oxide at large excess of water, generally on the order of 15 to 40 moles water to mole of alkylene oxide, with water generally comprising 85 weight percent of the reaction mixture. See, Kirk-Othmer Encyclopedia of Chemical Technology, 3rd. ed. (hereinafter "Kirk-Othmer"), Vol. 19 at 246-274 and 250.
Higher order alkylene glycols are generally produced either as by-products in the hydrolysis of monoalkylene oxides or as by-products in the production of lower order alkylene glycols, or are produced directly through one or more additions of an alkylene oxide with a lower order alkylene glycol.
For example, in the production of monopropylene glycol through the hydrolysis of propylene oxide at a large excess of water of 15 moles water/mole propylene oxide, the product mix is generally 85 percent propylene glycol, 13 percent dipropylene glycol, and 1.5 percent tripropylene glycol and higher adducts. See, Kirk-Othmer, Vol. 11 at 933-956 and 952.
Tripropylene glycol can also be obtained directly by the addition of propylene oxide to dipropylene glycol, generally in a catalyzed process. Since water is a competitor with the dipropylene glycol for the propylene oxide, its presence in the reaction mixture is to be avoided.
In the production of tripropylene glycol both primary and secondary hydroxyl groups are obtained. It is understood that the produced glycols will have either two primary hydroxyl groups, two secondary hydroxyl groups or one of each. As used herein the primary hydroxyl content is a percentage of the hydroxyl groups that are primary.
The primary hydroxyl group content obtained in the prior art propylene glycol processes is generally in the range of about 15 to about 36 percent. However, there is a need in the art for alkylene glycols having a higher primary hydroxyl group content.
There is also a need in the art for a process useful in providing alcohols, especially higher order alkylene glycols, having higher primary hydroxyl group content.
There is also a need in the art for an apparatus useful in providing alcohols, especially higher order alkylene glycols, having higher primary hydroxyl group content.
There is also a need in the art for a process useful in providing esters from alcohols and organic acids, the process having increased alcohol conversion and/or an increased reaction rate.